The effective disposal of hazardous radioactive waste materials is a continuing problem for industry. These waste materials can take a variety of forms including organic materials, which are combustible, and inorganic materials such as metal oxides, which are not combustible. Typically these wastes include ion exchange resins used in the nuclear industry and various articles of use such as clothing, paper and wood containers, rags, etc. The ion exchange resins are typically porous beads of polystyrene, cross-linked with divinyl benzene. These resins remove such compounds as borate, chloride, carbonate, and cesium ions and other fission and corrosion products from liquid streams.
Early systems employed the use of incinerators to burn waste materials. These incinerators had problems associated with ashes, produced by incomplete combustion, entrained in the off-gas. These airborne ashes thus presented an environmental hazard if not properly treated by filtering systems. Also, problems existed with high amounts of noncombustible leachable inorganics left behind in the bottom ash.
Various vitrification and incineration processes were employed to resolve the problems of the incineration processes. Such systems are set forth in U.S. Pat. Nos. 5,022,329; 4,666,490; 4,376,070; 4,424,149; 4,297,304; 4,299,611; 4,139,360; 4,020,004; 3,321,409 and in an article titled "Hazardous Waste: Where to Put It? Where Will It Go?", Mechanical Engineering, Sept. 1988, pgs. 70-75. These systems describe the vitrification of the ash product into a glass material to limit the leaching of the radionuclides from the ash using melters and cyclone furnaces. The cyclone furnace design in U.S. Pat. No. 5,022,329 requires the burning of fuels in order to combust the waste material instead of initiating combustion by contacting the waste material with a molten glass pool. The glass pool design is preferred in that the glass is heated by electrodes thereby reducing the dangers associated with the fuel heating of the cyclone furnace. The glass pool designs are deficient in that they do not ensure complete combustion in the plenum area above the glass pool, thus releasing combustible gases in the off-gas stream from the melter.
The neutralization and solidification of combustible sulfur compounds which are present in various waste materials is not disclosed in any of these systems. The sulfur compounds that are present in the combustion off-gases pose an environmental problem and should preferably be removed prior to gaseous emission to the atmosphere. The sulfur compounds are a major concern when treating ion exchange waste materials. Other methods of treating ion exchange waste materials is by resin dewatering and resin drying; however, these processes do not attain high levels of volume reduction and the final waste form is not solidified.
A need therefore exists to design a safe, efficient system for incinerating and vitrifrying radioactive waste materials. The system should also be designed to provide for proper disposal of sulfur compounds found within the waste material.